This invention relates to a disk adapter for a disk cartridge wherein disks of different diameters are to be accommodated within the disk cartridge.
There are known in the art recording and/or reproducing apparatus wherein recording and/or reproduction may be made on or from a disk-shaped recording medium, include optical disks dedicated to reproduction, such as a compact disk or a CD-ROM disk, or an optical disk on which information signals may be re-recorded, such as a magneto-optical disk. A disk cartridge accommodating a disk is known for example from the Japanese Utility Model Publication No. JP-A-63-153376(1988) which is provided with a lid that may be opened or closed with respect to the main body to permit the disk to be introduced or a taken out of the main body.
With such conventional disk cartridge, the available spacing for a disk including a disk rest is determined as a function of the diameter of the disk contained in the disk cartridge. Therefore, when a disk of a diameter different than usually employed disk is accommodated, the disk is moved within the disk rest such that, when the disk cartridge is attached to the main body of the recording and/or reproducing apparatus, not only can the disk not be placed on the disk table because the center of the disk table of the recording and/or reproducing apparatus is offset from the center of the disk, but also the disk cannot be chucked correctly, so that the recording and/or reproducing operation becomes unfeasible. When disk chucking is performed in the off center state, the disk area other than the chucking area, such as the signal recording area, is clamped between the chucking plate and the disk table provided in the recording and/or reproducing apparatus, so that the disk surface may be scored giving rise to errors during recording and/or reproduction.
As means for eliminating such deficiency, a disk adapter such as disclosed in the Japanese Patent Publication No. JP-A-64-1174(1989) may be employed. Since the adapter disclosed in this prior-art Publication is designed to hold the peripheral portion of the disk, the above described deficiency may be eliminated by mounting the adapter to the disk and accommodating the adapter-disk assembly in the disk cartridge.
However, since the adapter disclosed in the above Publication is designed simply to hold the outer periphery of the disk, the adapter may naturally be rotated in unison with the disk when the disk-adapter assembly is accommodated in the disk cartridge. However, when the adapter is attached incorrectly or when an impact is applied from outside, the disk may be easily disengaged from the adapter. With the disk thus disengaged from the adapter, there is the risk of the signal recording surface of the disk being scored or the disk being destroyed. There is also the risk of destruction of the disk driving mechanism of the recording and/or reproducing apparatus.